Scientists from Laser Physics Research Center of ITMO University developed a high-power laser with short pulse duration for lunar laser locator. The locator will allow measuring distance to the Moon with accuracy of a few millimeters. This would make it possible to correct calculations of celestial coordinates of the Moon in order to improve accuracy of satellite navigation. Description of the new laser was published in Optics Letters.
The principle of GPS and GLONASS systems is based on accurate measurement of the distance among several satellites and an object position of which is to be determined. Satellite coordinates should be known as accurately as possible. Since the large mass of the Moon affects trajectory of a satellite, when calculating its position lunar coordinates must be taken into account. The lunar coordinates are obtained by measuring the distance to the Moon with laser locators. The accuracy of laser locator depends on the laser pulse duration and resolution of the receiver.
Scientists from Laser Physics Research Center of ITMO University, the leader of Russian Academic Excellence Initiative (Project 5-100), developed a laser for lunar locator capable of measuring the distance to the Moon with accuracy of a few millimeters. The laser features relatively small size, low radiation divergence and a unique combination of short pulse duration, high pulse energy and high pulse repetition rate. The laser pulse duration is of 64 ps which is almost 16 billion times less than one second. The laser beam divergence which determines radiation brightness at large distance is near the theoretical limit being several times lower than that offered by analogues on the market.
“Actually, creation of a laser with pulse duration of tens of picoseconds is no longer technically difficult,” says Roman Balmashnov, engineer of Laser Physics Research Center and post-graduate student of the Photonics Megafaculty of ITMO University. “However, the output pulse energy of our laser is at least twice higher than that of analogues. It is 250 mJ at the “green” wavelenght and 430 mJ at the “infrared” wavelength. We managed to achieve high pulse repetition rate of 200 Hz and energy stability, so the pulse energy does not vary from pulse to pulse.”
The new laser will be used in lunar laser locator of the GLONASS navigation system. It will allow real-time updating of correction coefficients when calculating satellite coordinates and make russian satellite navigation system more accurate. The error of user positioning can be reduced to 10 cm.
“The laser we developed is a cutting edge technology for a set of parameters. According to our data, it is the most powerful pulse-periodic picosecond source of laser radiation in the world. In addition to strictly ranging applications, lasers of this class can be used for imaging of orbital objects: for example, satellites or space debris,” notes Andrey Mak, the Head of the Laser Physics Research Center of ITMO University.
A. F. Kornev, R. V. Balmashnov, I. G. Kuchma, A. S. Davtian, and D. O. Oborotov, “0.43 J/100 ps Nd:YAG laser with adaptive compensation of thermally induced lens,” Opt. Lett. 43, 4394-4397 (2018)